Elisabetta Bacchi

Both resistance training and aerobic training reduce hepatic fat content in type 2 diabetic subjects with nonalcoholic fatty liver disease (the RAED2 Randomized Trial).

Although lifestyle interventions are considered the first‐line therapy for nonalcoholic fatty liver disease (NAFLD), which is extremely common in people with type 2 diabetes, no intervention studies have compared the effects of aerobic (AER) or resistance (RES) training on hepatic fat content in type 2 diabetic subjects with NAFLD. In this randomized controlled trial, we compared the 4‐month effects of either AER or RES training on insulin sensitivity (by hyperinsulinemic euglycemic clamp), body composition (by dual‐energy X‐ray absorptiometry), as well as hepatic fat content and visceral (VAT), superficial (SSAT), and deep (DSAT) subcutaneous abdominal adipose tissue (all quantified by an in‐opposed‐phase magnetic resonance imaging technique) in 31 sedentary adults with type 2 diabetes and NAFLD. After training, hepatic fat content was markedly reduced (P < 0.001), to a similar extent, in both the AER and the RES training groups (mean relative reduction from baseline [95% confidence interval] −32.8% [−58.20 to −7.52] versus −25.9% [−50.92 to −0.94], respectively). Additionally, hepatic steatosis (defined as hepatic fat content >5.56%) disappeared in about one‐quarter of the patients in each intervention group (23.1% in the AER group and 23.5% in the RES group). Insulin sensitivity during euglycemic clamp was increased, whereas total body fat mass, VAT, SSAT, and hemoglobin A1c were reduced comparably in both intervention groups. Conclusion: This is the first randomized controlled study to demonstrate that resistance training and aerobic training are equally effective in reducing hepatic fat content among type 2 diabetic patients with NAFLD. (Hepatology 2013;58:1287–1295)

Metabolic Effects of Aerobic Training and Resistance Training in Type 2 Diabetic Subjects A randomized controlled trial (the RAED2 study)

OBJECTIVE To assess differences between the effects of aerobic and resistance training on HbA1c (primary outcome) and several metabolic risk factors in subjects with type 2 diabetes, and to identify predictors of exercise-induced metabolic improvement. RESEARCH DESIGN AND METHODS Type 2 diabetic patients (n = 40) were randomly assigned to aerobic training or resistance training. Before and after 4 months of intervention, metabolic phenotypes (including HbA1c, glucose clamp–measured insulin sensitivity, and oral glucose tolerance test–assessed β-cell function), body composition by dual-energy X-ray absorptiometry, visceral (VAT) and subcutaneous (SAT) adipose tissue by magnetic resonance imaging, cardiorespiratory fitness, and muscular strength were measured. RESULTS After training, increase in peak oxygen consumption (VO2peak) was greater in the aerobic group (time-by-group interaction P = 0.045), whereas increase in strength was greater in the resistance group (time-by-group interaction P < 0.0001). HbA1c was similarly reduced in both groups (−0.40% [95% CI −0.61 to −0.18] vs. −0.35% [−0.59 to −0.10], respectively). Total and truncal fat, VAT, and SAT were also similarly reduced in both groups, whereas insulin sensitivity and lean limb mass were similarly increased. β-Cell function showed no significant changes. In multivariate analyses, improvement in HbA1c after training was independently predicted by baseline HbA1c and by changes in VO2peak and truncal fat. CONCLUSIONS Resistance training, similarly to aerobic training, improves metabolic features and insulin sensitivity and reduces abdominal fat in type 2 diabetic patients. Changes after training in VO2peak and truncal fat may be primary determinants of exercise-induced metabolic improvement.

Exploring Muscle Activation during Nordic Walking: A Comparison between Conventional and Uphill Walking.

Nordic Walking (NW) owes much of its popularity to the benefits of greater energy expenditure and upper body engagement than found in conventional walking (W). Muscle activation during NW is still understudied, however. The aim of the present study was to assess differences in muscle activation and physiological responses between NW and W in level and uphill walking conditions. Nine expert Nordic Walkers (mean age 36.8±11.9 years; BMI 24.2±1.8 kg/m2) performed 5-minute treadmill trials of W and NW at 4 km/h on inclines of 0% and 15%. The electromyographic activity of seven upper body and five leg muscles and oxygen consumption (VO2) were recorded and pole force during NW was measured. VO2 during NW was 22.3% higher at 0% and only 6.9% higher at 15% than during W, while upper body muscle activation was 2- to 15-fold higher under both conditions. Lower body muscle activation was similarly increased during NW and W in the uphill condition, whereas the increase in erector spinae muscle activity was lower during NW than W. The lack of a significant increase in pole force during uphill walking may explain the lower extra energy expenditure of NW, indicating less upper body muscle activation to lift the body against gravity. NW seemed to reduce lower back muscle contraction in the uphill condition, suggesting that walking with poles may reduce effort to control trunk oscillations and could contribute to work production during NW. Although the difference in extra energy expenditure between NW and W was smaller in the uphill walking condition, the increased upper body muscle involvement during exercising with NW may confer additional benefit compared to conventional walking also on uphill terrains. Furthermore, people with low back pain may gain benefit from pole use when walking uphill.

Differences in the Acute Effects of Aerobic and Resistance Exercise in Subjects with Type 2 Diabetes: Results from the RAED2 Randomized Trial

Objective Both aerobic (AER) and resistance (RES) training, if maintained over a period of several months, reduce HbA1c levels in type 2 diabetes subjects. However, it is still unknown whether the short-term effects of these types of exercise on blood glucose are similar. Our objective was to assess whether there may be a difference in acute blood glucose changes after a single bout of AER or RES exercise. Study Design Twenty-five patients participating in the RAED2 Study, a RCT comparing AER and RES training in diabetic subjects, were submitted to continuous glucose monitoring during a 60-min exercise session and over the following 47 h. These measurements were performed after 10.9+0.4 weeks of training. Glucose concentration areas under the curve (AUC) during exercise, the subsequent night, and the 24-h period following exercise, as well as the corresponding periods of the non-exercise day, were assessed. Moreover, the low (LBGI) and high (HBGI) blood glucose indices, which summarize the duration and extent of hypoglycaemia or hyperglycaemia, respectively, were measured. Results AER and RES training similarly reduced HbA1c. Forty-eight hour glucose AUC was similar in both groups. However, a comparison of glucose AUC during the 60-min exercise period and the corresponding period of the non-exercise day showed that glucose levels were lower during exercise in the AER but not in the RES group (time-by-group interaction p = 0.04). Similar differences were observed in the nocturnal periods (time-by-group interaction p = 0.02). Accordingly, nocturnal LBGI was higher in the exercise day than in the non-exercise day in the AER (p = 0.012) but not in the RES group (p = 0.62). Conclusions Although AER and RES training have similar long-term metabolic effects in diabetic subjects, the acute effects of single bouts of these exercise types differ, with a potential increase in late-onset hypoglycaemia risk after AER exercise. Trial registration ClinicalTrials.gov NCT01182948

Supervised Walking Groups to Increase Physical Activity in Type 2 Diabetic Patients

OBJECTIVE To evaluate the impact of an exercise program organized into supervised walking groups in subjects with type 2 diabetes. RESEARCH DESIGN AND METHODS Fifty-nine diabetic subjects were randomized to a control group receiving standard lifestyle recommendations or an intervention group assigned to three supervised walking sessions per week and counseling. Changes in metabolic features, weight, 6-min walk test, prescription of antidiabetic medications, and overall physical activity were assessed. RESULTS Functional capacity and overall physical activity were higher in the intervention group, whereas metabolic changes were not different between groups after 4 months. However, in subjects who attended at least 50% of scheduled walking sessions, changes in A1C and fasting glucose were greater than in control subjects. Discontinuation or reduction of antidiabetic drugs occurred in 33% of these patients versus 5% of control subjects (P < 0.05). CONCLUSIONS Supervised walking may be beneficial in diabetic subjects, but metabolic improvement requires adequate compliance.

Exercise for Hepatic Fat Accumulation in Type 2 Diabetic Subjects

Type 2 diabetes is characterized by frequent ectopic fat accumulation in several tissues and organs. In particular, a number of studies showed that these subjects frequently have hepatic fat accumulation, which may play a role in the metabolic abnormalities typical of diabetes and has been also linked to increased risk for cardiovascular disease. In the last decade, the effect of exercise on ectopic fat content of type 2 diabetic patients has raised growing interest. However, there are only a few small randomized controlled trials on this topic. Results from these intervention studies indicate that exercise training, independent of dietary modifications, may reduce hepatic fat content and serum transaminases in these patients, suggesting that exercise per se may be an effective strategy to be combined with the traditional dietary interventions. As regards the different training modalities, there is recent evidence that both aerobic and resistance exercise may equally reduce hepatic fat accumulation in type 2 diabetic subjects. However, information regarding the effect of exercise on liver histology and fat accumulation in other ectopic sites is still very limited.

Physical Activity Patterns in Normal-Weight and Overweight/Obese Pregnant Women.

The aims of the present study were to assess the volume of physical activity (PA) throughout pregnancy in normal-weight vs overweight/obese women, and to investigate which factors may predict compliance to PA recommendations in these women throughout gestation. In 236 pregnant women, 177 normal-weight and 59 overweight/obese (median[IQR] BMI 21.2[19.9–22.8] vs 26.5[25.5–29.0] kg/m2, respectively), medical history, anthropometry and clinical data, including glucose tolerance, were recorded. In addition, pre-pregnancy PA was estimated by the Kaiser questionnaire, while total, walking and fitness/sport PA during pregnancy were assessed by the Physical Activity Scale for the Elderly (PASE) modified questionnaire, at 14–16, 24–28 and 30–32 weeks of gestation. PA volume was very low in the first trimester of pregnancy in both groups of women. However, it increased in the second and third trimester in normal-weight, but not in overweight/obese subjects. Higher pre-pregnancy PA was a statistically significant predictor of being physically active (>150 minutes of PA per week) during all trimesters of gestation. In conclusion, physical activity volume is low in pregnant women, especially in overweight/obese subjects. PA volume increases during pregnancy only in normal-weight women. Pre-pregnancy PA is an independent predictor of achieving a PA volume of at least 150 min per week during pregnancy.

Metabolic Effects of Exercise

Exercise has a powerful action on metabolism, and adaptation of the body to changes induced by exercise is fundamental to be able to provide the energy required for muscle contraction and physiological functions of vital tissues. Depending on the intensity and duration of exercise, different mechanisms are called on to make energy available, and under homeostatic control, this is guaranteed by rapid and coordinated changes in the secretion of several hormones. Molecular mechanisms controlling muscle function and fiber phenotype are related to the specific mode of muscle activation. We can distinguish between two fundamental types of physical activity, endurance exercise and strength exercise, although there is a continuum between these exercise modalities. Besides the acute changes induced by a single exercise session, regular exercise may induce chronic adaptations, improving exercise capacity and affecting energy metabolism. Notably, although acute metabolic effects of exercise are mostly due to insulin-independent effects, exercise training may improve muscle insulin sensitivity and is considered a key tool in the prevention and treatment of metabolic disorders. This chapter focuses on the biochemistry of energy supply to the exercising muscle, on molecular mechanisms involved and on the physiology of energy metabolism during exercise in healthy subjects and patients with insulin resistance and/or diabetes.

Influence of Acute Bouts of Exercise on Blood Glucose in Type 2 Diabetic Patients, as Measured by Continuous Glucose Monitoring Systems

Literature data indicate that the effect on blood glucose levels of a single bout of exercise may persist up to 48-h after cessation of exercise. Regular exercise improves insulin sensitivity and blood glucose control in subjects with type 2 diabetes and is considered a key element in the management of this condition. However, adaptive responses to exercise are altered in diabetic subjects and medications used in these patients may cause inappropriate insulin levels for the concurrent blood glucose concentrations, with a possible increase in risk for hypoglycaemia. Recently, the development and clinical availability of systems for the continuous monitoring of glucose (continuous glucose monitoring system, CGMS), have made it possible to continuously record blood glucose levels for several days in real life conditions, showing that possible differences in blood glucose levels of these individuals may occur during and after a single bout of exercise, depending on the characteristics of the physical activity. In particular, differences between aerobic vs resistance exercise and between low-intensity vs high-intensity exercise have been reported. However, there are only a few, small heterogeneous studies on this topic, and results are to some extent discordant, limiting any conclusions. Further research on this issue is needed before we can reach clear conclusions. In particular, the role of differences in frequency, duration, intensity, type and timing of exercise needs to be carefully investigated. Hopefully, this information will assist clinicians and exercise specialists in designing personalized exercise programmes and strategies aimed at optimally improving glucose control of type 2 diabetic patients, also limiting the risk for hypoglycaemia. In this article, we review the literature regarding the acute effect of different types of exercise on glucose levels, as measured by CGMS, in subjects with type 2 diabetes.

Effects of aerobic or resistance exercise training on cardiovascular autonomic function of subjects with type 2 diabetes: A pilot study

BACKGROUND AND AIMS Both aerobic (AER) and resistance (RES) training improve metabolic control in patients with type 2 diabetes (T2DM). However, information on the effects of these training modalities on cardiovascular autonomic control is limited. Our aim was to compare the effects of AER and RES training on cardiovascular autonomic function in these subjects. METHODS AND RESULTS Cardiovascular autonomic control was assessed by Power Spectral Analysis (PSA) of Heart Rate Variability (HRV) and baroreceptors function indexes in 30 subjects with T2DM, randomly assigned to aerobic or resistance training for 4 months. In particular, PSA of HRV measured the Low Frequency (LF) and High Frequency (HF) bands of RR variations, expression of prevalent sympathetic and parasympathetic drive, respectively. Furthermore, we measured the correlation occurring between systolic blood pressure and heart rate during a standardized Valsalva maneuver using two indexes, b2 and b4, considered an expression of baroreceptor sensitivity and peripheral vasoactive adaptations during predominant sympathetic and parasympathetic drive, respectively. After training, the LF/HF ratio, which summarizes the sympatho-vagal balance in HRV control, was similarly decreased in the AER and RES groups. After AER, b2 and b4 significantly improved. After RES, changes of b2 were of borderline significance, whereas changes of b4 did not reach statistical significance. However, comparison of changes in baroreceptor sensitivity indexes between groups did not show statistically significant differences. CONCLUSION Both aerobic and resistance training improve several indices of the autonomic control of the cardiovascular system in patients with T2DM. Although these improvements seem to occur to a similar extent in both training modalities, some differences cannot be ruled out. CLINICAL TRIAL REGISTRATION NUMBER NCT01182948, clinicaltrials.gov.